• • Co-combustion of coal gangue with corn stalk reduces apparent activation energy and increases aluminum leaching yield to 81.9%, enabling economically viable recovery from waste streams.
• • Titanium and iron ions in the leachate act as natural morphology regulators, steering alumina crystallization toward plate-like α-Al2O3 with d50 = 5.70 μm, eliminating the need for synthetic additives.
• • A high relative content of AlO6 structural units in the precursor promotes direct conversion to dense α-Al2O3, achieving a product density of 4.94 g/cm3, which is critical for refractory and abrasive applications.
• • The integrated process—co-combustion activation, acid leaching, and molten salt synthesis—simplifies conventional purification steps, offering a short-process route for high-value alumina production from solid wastes.